Loladze and a handful of other scientists have come to suspect that’s not the whole story and that the atmosphere itself may be changing the food we eat. Plants need carbon dioxide to live like humans need oxygen. And in the increasingly polarized debate about climate science, one thing that isn’t up for debate is that the level of CO2 in the atmosphere is rising. Before the industrial revolution, the earth’s atmosphere had about 280 parts per million of carbon dioxide. Last year, the planet crossed over the 400 parts per million threshold; scientists predict we will likely reach 550 parts per million within the next half-century—essentially twice the amount that was in the air when Americans started farming with tractors.

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In 2014, Myers and a team of other scientists published a large, data-rich study in the journal Nature that looked at key crops grown at several sites in Japan, Australia and the United States that also found rising CO2 led to a drop in protein, iron and zinc. It was the first time the issue had attracted any real media attention.

“The public health implications of global climate change are difficult to predict, and we expect many surprises,” the researchers wrote. “The finding that raising atmospheric CO2 lowers the nutritional value of C3 crops is one such surprise that we can now better predict and prepare for.”